Derivation of Apparent Diffusion Coefficient based on Time Variation of the Relaxation Mass Depths of Cs-137 in Soil Contaminated by the Fukushima NPP Accident

MRS Advances ◽  
2019 ◽  
Vol 4 (17-18) ◽  
pp. 1001-1007
Author(s):  
Haruo Sato ◽  
Masaharu Hirota
Keyword(s):  
Time Variation ◽  
Ground Surface ◽  
Vertical Direction ◽  
Fukushima Prefecture ◽  
Apparent Diffusion Coefficients ◽  
Elapsed Time ◽  
Field Investigations ◽  
Apparent Diffusion ◽  
Relaxation Depth ◽  
Almost All

ABSTRACTThe accident at the Fukushima Dai-ichi Nuclear Power Plant occurred following the Great East Japan Earthquake on March 11, 2011, and led to the release of volatile radionuclides, which were deposited on the environment in the Fukushima prefecture and the neighbouring areas. After the short-lived I-131, radiocaesium such as Cs-134 and Cs-137 have controlled radiation dose rate. The authors derived the apparent diffusion coefficients (Da) of some radionuclides such as Cs-134 and Cs-137 based on time variation of the depth distributions of respective radionuclides in soil obtained in field investigations in earlier studies. Almost all Da-values were of order 10-14 (m2·s−1) and well consistent with distribution coefficients (Kd) obtained from batch experiments. Whilst, field investigations for the relaxation mass depths of Cs-137 in soil by a scraper plate method were conducted at totally 85 locations over a period of nearly 6 years from December 2011 in the Fukushima prefecture and the neighbouring prefectures, and time variation of the effective relaxation mass depths was recently reported. Consequently, the effective relaxation mass depths of Cs-137 showed a tendency to linearly increase with increasing time. This indicates that radiocaesium gradually moves to the deeper part of soil with time. In this study, Da based on Fick’s diffusion equation was derived based on time variation of the effective relaxation mass depths of Cs-137 in soil. In order to calculate the Da based on Fick’s law, correlation between relaxation depth and square root of elapsed time was derived from the correlation between effective relaxation mass depth and elapsed time (where, relaxation depth is defined as the depth of 1/e of radionuclide concentration at the ground surface and can calculate by relaxation mass depth/soil density). The calculated Da of Cs-137 was of order 10-12 (m2·s−1) , which was about 2 orders of magnitude higher than Da-values that the authors previously reported as described above. Considering that almost all relaxation depths of Cs-137 were shallow within 2cm in depth from the ground surface and near the surface layer of soil is unsaturated, it is considered that Da estimated in this analysis includes the effect of dispersion by advection (by flow in the vertical direction of rainwater).

Baseline apparent diffusion coefficients: Validation study of new predictor of survival in patients with unresectable hepatocellular carcinoma following chemoembolization

2021 ◽  
pp. 1-10
Author(s):  
Lichao Xu ◽  
Shiqin Wang ◽  
Shengping Wang ◽  
Ying Wang ◽  
Wentao Li ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Roc Curve ◽  
Cox Regression ◽  
Response To Treatment ◽  
Roc Curve Analysis ◽  
Adc Value ◽  
Apparent Diffusion Coefficients ◽  
Apparent Diffusion ◽  
Response Biomarker ◽  
The Difference

OBJECTIVES: To investigate whether the baseline apparent diffusion coefficient (ADC) can predict survival in the hepatocellular carcinoma (HCC) patients receiving chemoembolization. MATERIALS AND METHODS: Diffusion-weighted MR imaging of HCC patients is performed within 2 weeks before chemoembolization. The ADC of the largest index lesion is recorded. Responses are assessed by mRECIST after the start of the second course of chemoembolization. Receiver operating characteristic (ROC) curve analysis is performed to evaluate the diagnostic performance and determine optimal cut-off values. Cox regression and Kaplan–Meier survival analyses are used to explore the differences in overall survival (OS) between the responders and non-responders. RESULTS: The difference is statistically significant in the baseline ADC between the responders and non-responders (P <  0.001). ROC analyses indicate that the baseline ADC value is a good predictor of response to treatment with an area under the ROC curve (AUC) of 0.744 and the optimal cut-off value of 1.22×10–3 mm2/s. The Cox regression model shows that the baseline ADC is an independent predictor of OS, with a 57.2% reduction in risk. CONCLUSION: An optimal baseline ADC value is a functional imaging response biomarker that has higher discriminatory power to predict tumor response and prolonged survival following chemoembolization in HCC patients.

scholarly journals Classification of paediatric brain tumours by diffusion weighted imaging and machine learning

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jan Novak ◽  
Niloufar Zarinabad ◽  
Heather Rose ◽  
Theodoros Arvanitis ◽  
Lesley MacPherson ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Apparent Diffusion Coefficient ◽  
Posterior Fossa ◽  
Brain Tumours ◽  
Diffusion Weighted Imaging ◽  
Regions Of Interest ◽  
Apparent Diffusion Coefficients ◽  
Diffusion Weighted ◽  
Apparent Diffusion ◽  
Paediatric Brain Tumours

AbstractTo determine if apparent diffusion coefficients (ADC) can discriminate between posterior fossa brain tumours on a multicentre basis. A total of 124 paediatric patients with posterior fossa tumours (including 55 Medulloblastomas, 36 Pilocytic Astrocytomas and 26 Ependymomas) were scanned using diffusion weighted imaging across 12 different hospitals using a total of 18 different scanners. Apparent diffusion coefficient maps were produced and histogram data was extracted from tumour regions of interest. Total histograms and histogram metrics (mean, variance, skew, kurtosis and 10th, 20th and 50th quantiles) were used as data input for classifiers with accuracy determined by tenfold cross validation. Mean ADC values from the tumour regions of interest differed between tumour types, (ANOVA P < 0.001). A cut off value for mean ADC between Ependymomas and Medulloblastomas was found to be of 0.984 × 10−3 mm2 s−1 with sensitivity 80.8% and specificity 80.0%. Overall classification for the ADC histogram metrics were 85% using Naïve Bayes and 84% for Random Forest classifiers. The most commonly occurring posterior fossa paediatric brain tumours can be classified using Apparent Diffusion Coefficient histogram values to a high accuracy on a multicentre basis.

scholarly journals Heterogeneity of Apparent Diffusion Coefficients Within Infarcts

Stroke ◽  
2001 ◽  
Vol 32 (7) ◽  
pp. 1695-1696
Author(s):  
Pratik Mukherjee ◽  
Robert C. McKinstry ◽  
Joshua S. Shimony ◽  
Erbil Akbudak ◽  
Abraham Z. Snyder ◽  
...  
Keyword(s):  
Diffusion Coefficients ◽  
Apparent Diffusion Coefficients ◽  
Apparent Diffusion

Minimum apparent diffusion coefficients in the evaluation of brain tumors

2005 ◽  
Vol 55 (3) ◽  
pp. 393-400 ◽  
Author(s):  
Omer Kitis ◽  
Hakan Altay ◽  
Cem Calli ◽  
Nilgun Yunten ◽  
Taner Akalin ◽  
...  
Keyword(s):  
Brain Tumors ◽  
Diffusion Coefficients ◽  
Apparent Diffusion Coefficients ◽  
Apparent Diffusion

scholarly journals Chloride Ingress in Chemically Activated Calcined Clay-Based Cement

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Joseph Mwiti Marangu ◽  
Joseph Karanja Thiong’o ◽  
Jackson Muthengia Wachira
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Ordinary Portland Cement ◽  
Strength Development ◽  
Chloride Ingress ◽  
Calcined Clay ◽  
Apparent Diffusion Coefficients ◽  
Apparent Diffusion ◽  
Lower Porosity ◽  
Lower Chloride

Chloride-laden environments pose serious durability concerns in cement based materials. This paper presents the findings of chloride ingress in chemically activated calcined Clay-Ordinary Portland Cement blended mortars. Results are also presented for compressive strength development and porosity tests. Sampled clays were incinerated at a temperature of 800°C for 4 hours. The resultant calcined clay was blended with Ordinary Portland Cement (OPC) at replacement level of 35% by mass of OPC to make test cement labeled PCC35. Mortar prisms measuring 40 mm × 40 mm × 160 mm were cast using PCC35 with 0.5 M Na2SO4 solution as a chemical activator instead of water. Compressive strength was determined at 28th day of curing. As a control, OPC, Portland Pozzolana Cement (PPC), and PCC35 were similarly investigated without use of activator. After the 28th day of curing, mortar specimens were subjected to accelerated chloride ingress, porosity, compressive strength tests, and chloride profiling. Subsequently, apparent diffusion coefficients (Dapp) were estimated from solutions to Fick’s second law of diffusion. Compressive strength increased after exposure to the chloride rich media in all cement categories. Chemically activated PCC35 exhibited higher compressive strength compared to nonactivated PCC35. However, chemically activated PCC35 had the least gain in compressive strength, lower porosity, and lower chloride ingress in terms of Dapp, compared to OPC, PPC, and nonactivated PCC35.

scholarly journals Accuracy of apparent diffusion coefficients and enhancement ratios on magnetic resonance imaging in differentiating primary cerebral lymphomas from glioblastoma

2019 ◽  
Vol 32 (5) ◽  
pp. 328-334 ◽  
Author(s):  
Shayan Sirat Maheen Anwar ◽  
Mirza Zain Baig ◽  
Altaf Ali Laghari ◽  
Fatima Mubarak ◽  
Muhammad Shahzad Shamim ◽  
...  
Keyword(s):  
Operating Characteristic ◽  
Characteristic Curve ◽  
Area Under The Curve ◽  
Regions Of Interest ◽  
Post Contrast ◽  
Apparent Diffusion Coefficients ◽  
Normal Appearing White Matter ◽  
Apparent Diffusion ◽  
Adc Values ◽  
Patient Subgroups

Background and purposeThis study aimed to determine the accuracy of apparent diffusion coefficient (ADC) and enhancement ratio (ER) in discriminating primary cerebral lymphomas (PCL) and glioblastomas.Materials and methodsCircular regions of interest were randomly placed centrally within the largest solid-enhancing area of all lymphomas and glioblastomas on both post-contrast T1-weighted images and corresponding ADC maps. Regions of interest were also drawn in the contralateral hemisphere to obtain enhancement and ADC values of normal-appearing white matter. This helped us to calculate the ER and ADC ratio.ResultsMean enhancement and ADC (mm2/s) values for PCL were 2220.56 ± 2948.30 and 712.00 ± 137.87, respectively. Mean enhancement and ADC values for glioblastoma were 1537.07 ± 1668.33 and 1037.93 ± 280.52, respectively. Differences in ADC values, ratios and ERs were all statistically significant between the two groups ( p < 0.05). ADC values correctly predicted 71.4% of the lesions as glioblastoma and 83.3% as PCL (area under the curve (AUC) = 0.86 on receiver operating characteristic curve analysis). ADC ratios correctly predicted 85.7% of the lesions as glioblastoma and 100% as PCL (AUC = 0.93). ERs correctly predicted 71.4% of the lesions as glioblastoma and 88.9% as PCL (AUC = 0.92). The combination of ADC ratio and ER correctly predicted 100% tumour type in both patient subgroups.ConclusionsADC values, ADC ratios and ERs may serve as useful variables to distinguish PCL from glioblastoma. The combination of ADC ratio and ER yielded the best results in identification of both patient subgroups.

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